Just wanted to share my recent experiences dealing with Tribulant after buying their WordPress Newsletter Plugin. They're not great.
The short version is the plugin doesn't work out of the box with Weaver. They offered to edit the theme for me which was nice, but I don't like breaking auto-updates so I declined.
Unfortunately, they've been very stubborn about offering me a refund. There are no issues with piracy since the plugin does a serial check with their servers whenever it runs. Cancel the serial key and it's useless.
So I naturally assumed if it didn't work they'd be happy to give me a refund. I didn't think to look at their "no refunds" statement which is in "Policies" under the "Support" section (isn't "Support" normally something you click on AFTER you've bought something?). And there were certainly no mention of this policy on the plugin or checkout page.
They offered me a "credit", but if you're only interested in the one product a credit is as good as keeping the money.
To top it off, when I politely brought these points up with them, they just stopped responding to my support emails.
Very, very disappointing guys. You don't offer a demo version to try despite the fact that it's serial-protected, don't make your refund policy obvious to new customers.